Got it working. Here is working signature settings and last photo have settings how to get servertime.
Copy paste signature (update your key and modules): {{sha256(“timestamp=” + (18.data.serverTime + 1000); “hex”; 25.TESTNET SECRET KEY)}}
I hope this helps someone.
Cheers!
EDIT: This was good tool for confirm SHA256 hashing: Free Online HMAC Generator / Checker Tool (MD5, SHA-256, SHA-512) - FreeFormatter.com
